[panshuai@localhost Documents]$ cat a.txt?

id name gender mark

1 aa f 80

2 bb f 81

3 cc f 82

4 dd f 83

id:name:gender:mark

5:ee:t:11

6:ff:t:12

7:gg:t:13

8:hh:t:14

[panshuai@localhost Documents]$ cut -f 3 a.txt?

gender

f

f

f

f

id:name:gender:mark

5:ee:t:11

6:ff:t:12

7:gg:t:13

8:hh:t:14

[panshuai@localhost Documents]$ cut -f 3 -d ":" a.txt?

id name gender mark

1 aa f 80

2 bb f 81

3 cc f 82

4 dd f 83

gender

t

t

t

t

[panshuai@localhost Documents]$?

為什么會(huì)出現(xiàn)這個(gè)情況？會(huì)多出那些不需要的行